C library function - ferror()

Description

The C library function int ferror(FILE *stream) tests the error indicator for the given stream.

Declaration

Following is the declaration for ferror() function.

int ferror(FILE *stream)

Parameters

• stream − This is the pointer to a FILE object that identifies the stream.

Return Value

If the error indicator associated with the stream was set, the function returns a non-zero value else, it returns a zero value.

Example

The following example shows the usage of ferror() function.

#include <stdio.h>

int main () {
   FILE *fp;
   char c;

   fp = fopen("file.txt", "w");

   c = fgetc(fp);
   if( ferror(fp) ) {
      printf("Error in reading from file : file.txt\n");
   }
   clearerr(fp);
   
   if( ferror(fp) ) {
      printf("Error in reading from file : file.txt\n");
   }
   fclose(fp);

   return(0);
}

Assuming we have a text file file.txt, which is an empty file. Let us compile and run the above program that will produce the following result because we try to read a file which we opened in write only mode.

Error reading from file "file.txt"